Unaudited Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 29, 2012	Sep. 29, 2012	Jun. 23, 2012	Mar. 24, 2012	Dec. 24, 2011	Sep. 27, 2014	Sep. 28, 2013	Sep. 29, 2012
Unaudited Quarterly Financial Data
Length of fiscal period	91 days	91 days	91 days	91 days	91 days	91 days	91 days	91 days	98 days	91 days	91 days	91 days	364 days	364 days	371 days
Net sales	$ 1,195,567	$ 1,022,371	$ 1,103,072	$ 1,386,670	$ 1,047,177	$ 967,072	$ 1,004,792	$ 1,339,059	$ 946,736	$ 869,194	$ 885,052	$ 1,158,216	$ 4,707,680	$ 4,358,100	$ 3,859,198
Gross profit	449,789	444,592	457,432	464,047	377,459	407,618	415,146	419,163	316,446	303,311	313,038	336,604	1,815,860	1,619,386	1,269,399
Net income attributable to GMCR	$ 141,056	$ 155,151	$ 162,084	$ 138,227	$ 126,956	$ 116,272	$ 132,421	$ 107,583	$ 91,887	$ 73,296	$ 93,031	$ 104,414	$ 596,518	$ 483,232	$ 362,628
Basic (in dollars per share)	$ 0.87	$ 0.95	$ 1.05	$ 0.93	$ 0.84	$ 0.78	$ 0.89	$ 0.72	$ 0.59	$ 0.47	$ 0.60	$ 0.67	$ 3.80	$ 3.23	$ 2.34
Diluted (in dollars per share)	$ 0.86	$ 0.94	$ 1.03	$ 0.91	$ 0.83	$ 0.76	$ 0.87	$ 0.70	$ 0.58	$ 0.46	$ 0.58	$ 0.66	$ 3.74	$ 3.16	$ 2.28
Dividend paid per share (in dollars per share)	$ 0.25	$ 0.25	$ 0.25